Japanese Patent Application Publication No. 2003-343491 and Japanese Patent Application Publication No. 2003-28092 disclose seal structures which seal the gap between a housing and a rotary shaft of a water pump device by use of a packing. This packing includes an annular lip that comes into sliding contact with the outer circumferential surface of the rotary shaft.
Japanese Patent Application Publication No. 2004-19782 and Japanese Patent Application Publication No. 2000-9106 disclose seal structures which seal the gap between a cylinder body and a piston rod of a cylinder device by use of a packing. This packing includes an annular lip that comes into sliding contact with the outer circumferential surface of the piston rod.